127 lines
4.6 KiB
JavaScript
127 lines
4.6 KiB
JavaScript
// @tags: [requires_getmore, assumes_balancer_off]
|
|
|
|
// Test subtleties of batchSize and limit.
|
|
|
|
(function() {
|
|
"use strict";
|
|
load("jstests/libs/fixture_helpers.js"); // For FixtureHelpers.
|
|
var t = db.jstests_batch_size;
|
|
t.drop();
|
|
|
|
for (var i = 0; i < 4; i++) {
|
|
t.save({_id: i, a: i});
|
|
}
|
|
|
|
function runIndexedTests() {
|
|
// With limit, indexed.
|
|
assert.eq(2, t.find().limit(2).itcount());
|
|
assert.eq(2, t.find().sort({a: 1}).limit(2).itcount());
|
|
|
|
// With batchSize, indexed.
|
|
// SERVER-12438: If there is an index that provides the sort, then a plan with an unindexed
|
|
// sort should never be used. Consequently, batchSize will NOT be a hard limit in this
|
|
// case. WARNING: the behavior described above may change in the future.
|
|
assert.eq(4, t.find().batchSize(2).itcount());
|
|
assert.eq(4, t.find().sort({a: 1}).batchSize(2).itcount());
|
|
}
|
|
|
|
// Without batch size or limit, unindexed.
|
|
assert.eq(4, t.find().itcount());
|
|
assert.eq(4, t.find().sort({a: 1}).itcount());
|
|
|
|
// With limit, unindexed.
|
|
assert.eq(2, t.find().limit(2).itcount());
|
|
assert.eq(2, t.find().sort({a: 1}).limit(2).itcount());
|
|
|
|
assert.eq(4, t.find().batchSize(2).itcount());
|
|
assert.eq(4, t.find().sort({a: 1}).batchSize(2).itcount());
|
|
|
|
// With negative batchSize. A negative batchSize value instructs the server
|
|
// to return just a single batch of results.
|
|
assert.eq(1, t.find().batchSize(-1).itcount());
|
|
assert.eq(2, t.find().batchSize(-2).itcount());
|
|
|
|
// Run the tests with the index twice in order to double check plan caching.
|
|
t.ensureIndex({a: 1});
|
|
for (var i = 0; i < 2; i++) {
|
|
runIndexedTests();
|
|
}
|
|
|
|
// The next tests make sure that we obey limit and batchSize properly when the sort could be
|
|
// either indexed or unindexed.
|
|
t.drop();
|
|
t.ensureIndex({a: 1});
|
|
t.ensureIndex({b: 1});
|
|
|
|
for (var i = 0; i < 100; i++) {
|
|
t.save({_id: i, a: i, b: 1});
|
|
}
|
|
|
|
// Without a hint. Do it twice to make sure caching is ok.
|
|
for (var i = 0; i < 2; i++) {
|
|
assert.eq(15, t.find({a: {$gte: 85}}).sort({b: 1}).batchSize(2).itcount());
|
|
assert.eq(6, t.find({a: {$gte: 85}}).sort({b: 1}).limit(6).itcount());
|
|
}
|
|
|
|
// Hinting 'a'.
|
|
assert.eq(15, t.find({a: {$gte: 85}}).sort({b: 1}).hint({a: 1}).batchSize(2).itcount());
|
|
assert.eq(6, t.find({a: {$gte: 85}}).sort({b: 1}).hint({a: 1}).limit(6).itcount());
|
|
|
|
// Hinting 'b'.
|
|
assert.eq(15, t.find({a: {$gte: 85}}).sort({b: 1}).hint({b: 1}).batchSize(2).itcount());
|
|
assert.eq(6, t.find({a: {$gte: 85}}).sort({b: 1}).hint({b: 1}).limit(6).itcount());
|
|
|
|
// With explain.
|
|
var explain = t.find({a: {$gte: 85}}).sort({b: 1}).batchSize(2).explain("executionStats");
|
|
assert.eq(15, explain.executionStats.nReturned);
|
|
explain = t.find({a: {$gte: 85}}).sort({b: 1}).limit(6).explain("executionStats");
|
|
if (FixtureHelpers.isMongos(db)) {
|
|
// If we're talking to a mongos, we expect at most one batch from each shard.
|
|
assert.eq(FixtureHelpers.numberOfShardsForCollection(t) * 6, explain.executionStats.nReturned);
|
|
} else {
|
|
assert.eq(6, explain.executionStats.nReturned);
|
|
}
|
|
|
|
// Double check that we're not scanning more stuff than we have to. In order to get the sort
|
|
// using index 'a', we should need to scan about 50 keys and 50 documents.
|
|
var explain = t.find({a: {$gte: 50}}).sort({b: 1}).hint({a: 1}).limit(6).explain("executionStats");
|
|
assert.lte(explain.executionStats.totalKeysExamined, 60);
|
|
assert.lte(explain.executionStats.totalDocsExamined, 60);
|
|
if (FixtureHelpers.isMongos(db)) {
|
|
// If we're talking to a mongos, we expect at most one batch from each shard.
|
|
assert.eq(FixtureHelpers.numberOfShardsForCollection(t) * 6, explain.executionStats.nReturned);
|
|
} else {
|
|
assert.eq(6, explain.executionStats.nReturned);
|
|
}
|
|
|
|
// -------
|
|
|
|
// During plan ranking, we treat ntoreturn as a limit. This prevents us from buffering too much
|
|
// data in a blocking sort stage during plan ranking.
|
|
t.drop();
|
|
|
|
// Generate big string to use in the object - 1MB+ String
|
|
var bigStr = "ABCDEFGHIJKLMNBOPQRSTUVWXYZ012345687890";
|
|
while (bigStr.length < 1000000) {
|
|
bigStr = bigStr + "::" + bigStr;
|
|
}
|
|
|
|
// Insert enough documents to exceed the 32 MB in-memory sort limit.
|
|
const nDocs = 40 * FixtureHelpers.numberOfShardsForCollection(t);
|
|
for (var i = 0; i < nDocs; i++) {
|
|
var doc = {x: 1, y: 1, z: i, big: bigStr};
|
|
t.insert(doc);
|
|
}
|
|
|
|
// Two indices needed in order to trigger plan ranking. Neither index provides the sort order.
|
|
t.ensureIndex({x: 1});
|
|
t.ensureIndex({y: 1});
|
|
|
|
// We should only buffer 3 docs in memory.
|
|
var cursor = t.find({x: 1, y: 1}).sort({z: -1}).limit(3);
|
|
assert.eq(nDocs - 1, cursor.next().z);
|
|
assert.eq(nDocs - 2, cursor.next().z);
|
|
assert.eq(nDocs - 3, cursor.next().z);
|
|
assert(!cursor.hasNext());
|
|
}());
|